---

Lesson 7: Functions and Modules | Coding Class Series

Introduction

Welcome to Lesson 7!
In this lesson, we will learn about functions and modules in Python. Functions allow you to reuse code, while modules help you organize your programs efficiently.

---

1. Functions

A function is a block of code that performs a specific task and can be reused multiple times.

Syntax:

def greet(name):
    print(f"Hello, {name}!")

greet("Alice")  # Output: Hello, Alice!

Key Points:

• Functions start with the def keyword.
• Arguments can be passed inside parentheses.
• return keyword is used to give back a result.

Example with Return:

def add(a, b):
    return a + b

result = add(5, 3)
print(result)  # Output: 8

---

2. Modules

A module is a file containing Python definitions and functions.
You can import modules to use their functions in your program.

Importing a module:

import math

print(math.sqrt(16))  # Output: 4.0

From module import specific function:

from math import pow

print(pow(2, 3))  # Output: 8.0

Creating your own module:

1. Create a file my_module.py:

def welcome():
    print("Welcome to my module!")

2. Import in another file:

import my_module

my_module.welcome()  # Output: Welcome to my module!

---

3. Advantages of Functions and Modules

• Reusability: Write once, use multiple times.
• Organization: Keeps code clean and structured.
• Efficiency: Saves time and reduces errors.
• Scalability: Easier to maintain and expand large programs.

---

Practice Exercises

1. Create a function multiply(a, b) that returns the product of two numbers.
2. Write a function that takes a list of numbers and returns the largest number.
3. Create a module math_utils.py with a function square(n) that returns the square of a number. Import it and test.
4. Use the random module to generate 5 random numbers between 1 and 50.

---